Sample measuring device

ABSTRACT

An adapter is attached to each sample storage unit in a rack. Each adapter includes a pair of arms, and these arms include a pair of lower-end structural bodies. An opening force being imparted to a pair of the lower-end structural bodies in the horizontal direction when a sample container is mounted on the pair of lower-end structural bodies causes the bodies to retreat towards the outside in the horizontal direction. In the subsequent opened state, the sample container is passed from the rack to a lifting mechanism. In the closed state, pressure being applied to the sample container in the vertical direction causes a stopper segment, which is contained in each attachment, to be lowered. In this lowered state, the opening motion of the pair of arms is restricted.

TECHNICAL FIELD

The present invention relates to a sample measurement device, and inparticular, to a sample measurement device which measures a radioactivesubstance in a sample using a liquid scintillator.

BACKGROUND ART

A sample measurement device is a device that individually measures aplurality of samples. Representative sample measurement devices includea liquid scintillation counter. The liquid scintillation counter has arack-transporting mechanism which transports a rack holding a pluralityof sample containers, a measurement unit which measures light caused bya radioactive substance contained in each sample container, a containertransporting mechanism which transports the sample container between therack and a measurement chamber unit, or the like. In the samplecontainer, in addition to liquid sample, liquid scintillator isincluded. When a radiation (for example, a β ray) is emitted from theradioactive substance in the sample, light emission in the liquidscintillator is caused by the radiation. The light is detected by a pairof photomultiplier tubes forming the measurement unit.

In general, a shielding structure must be provided in order to block anextrinsic radiation at a periphery of a measurement chamber which storesthe sample container to be measured. Such a shielding structure isformed from a metal which is very heavy. Therefore, it is morepreferable that the shielding structure be placed below a rack placementsurface rather than being placed above the rack placement surface. Inaddition, when a system is employed in which the sample container istransported upward from the rack, because a shaft which supports thesample container would exist within a lifting/lowering path during themeasurement, there is a problem in that light shielding in thelifting/lowing path is difficult. Therefore, it is desired that themeasurement chamber be provided below the rack placement surface, andalso to withdraw the sample container downward from the rack.

Patent Document 1 discloses a liquid scintillation counter of therelated art. In the liquid scintillation counter described therein, themeasurement chamber is provided above a transport table for transportingthe rack. Patent Document 2 discloses a rack transporting device whichcan be used for the liquid scintillation counter or the like.

CITATION LIST Patent Literature

-   [Patent Document 1] JP 2007-278969 A-   [Patent Document 2] JP 2007-176666 A

SUMMARY Technical Problem

When a system is employed to withdraw the sample container downward fromthe rack, a mechanism for holding and releasing the sample containermust be provided for each sample storage unit in the rack. As such amechanism, it is desired to employ a mechanism which is as simple aspossible. On the other hand, it is also necessary to prevent falling-offof the sample container even when the pressing force is applied on thesample container from above the container due to an erroneous operationby the user or the like. Thus, a scheme is desired which prevent thedevice from easily assuming an open state.

An advantage of the present invention is in the prevention offalling-off of the sample container from the rack. In particular, amechanism is realized in which the sample container does not easily falloff from the rack even when a pressing force is applied on the samplecontainer from above the sample container.

Solution to Problem

According to one aspect of the present invention, there is provided asample measurement device, comprising: a rack having a sample storageunit; a transporting mechanism that transports the rack; and anopen/close mechanism provided in the sample storage unit that holds asample container in a closed state and that releases the samplecontainer in an open state, wherein the open/close mechanism changesfrom the closed state to the open state when an opening force in ahorizontal direction is received, and maintains the closed state when apressing force in a vertical direction is received through the samplecontainer.

According to the above-described configuration, the rack has at leastone sample storage unit, and the open/close mechanism that holds andreleases the sample container is provided in the sample storage unit.When an opening force in the horizontal direction is applied on theopen/close mechanism, the open/close mechanism changes from the closedstate to the open state. With such a configuration, it becomes possibleto withdraw the sample container downward from the sample storage unit.When the opening force in the horizontal direction on the open/closemechanism disappears, the open/close mechanism is returned from the openstate to the closed state by, for example, an elastic recovery force ofthe open/close mechanism. With such a configuration, the samplecontainer is again held. On the other hand, when a pressing force isapplied from above the sample container toward the downward direction ina state where the open/close mechanism is in the closed state (that is,in the sample container holding state), the pressing force istransmitted to the open/close mechanism. However, if the pressing forcein the vertical direction is within a presumed range, the open/closemechanism is not opened by the pressing force. Therefore, thefalling-off of the sample container due to the pressing force isprevented. As described, the open/close mechanism executes differentoperations depending on the type of the force applied thereto (inparticular, the direction of the force). In particular, the open/closemechanism has a scheme to prevent the opening operation with regard to apressing force from above toward below. Alternatively, variousstructures may be employed as a structure or a means to prevent theopening operation by the pressing force.

According to another aspect of the present invention, preferably, in thesample measurement device, the open/close mechanism has: a movablemember that supports a lower surface of the sample container at animmediately-below position of the sample container in the closed state,and that moves from the immediately-below position to a retractedposition deviated to an outer side in the horizontal direction during astate change from the closed state to the open state; and a deformationmember that deforms by a pressing force when the pressing force isapplied, so as to restrict movement of the movable member to theretracted position. The movable member functions as a base for thesample container in the closed state. That is, the movable membersupports the lower surface of the ample container in the closed state.The movable member moves to the retracted position deviated to the outerside in the horizontal direction from the immediate-below position ofthe sample container in the open state. With this configuration, itbecomes possible to withdraw the sample container downward from thesample storage unit. When the pressing force in the vertical directionis applied on the sample container, the deformation member is deformedby the pressing force. That is, a position or a form of all or a part ofthe open/close mechanism changes. The opening movement of the movablemember in the horizontal direction is limited utilizing this change.

According to another aspect of the present invention, preferably, in thesample measurement device, the open/close mechanism has a pair of arms,the movable member is formed by a pair of lower ends of the pair of thearms, and the deformation member is formed by a pair of deformationportions of the pair of the lower ends. Each deformation portion may beformed as a portion having a C shape or a U shape. Alternatively, thedeformation portion may be formed as a portion that falls toward theinner side in the horizontal direction by the pressing force. Theopening direction of the pair of the arms may be a longitudinaldirection of the rack or a short-side direction of the rack. When thepair of arms is opened in the longitudinal direction, the pair of armsmust be moved such that the pair of arms do not collide with theadjacent sample container. When the pair of arms is opened in theshort-side direction, such a collision can be avoided. In this case, therack body and the peripheral mechanism are preferably configured toallow the opening movement of the pair of arms.

According to another aspect of the present invention, preferably, in thesample measurement device, each of the arms has: an upper end connectedto a body of the rack; a bending portion that is a portion continuousfrom a lower side of the upper end and that elastically bends toward anouter side in the horizontal direction in the open state; and a lowerend that is continuous from a lower side of the bending portion and thatis one of the pair of the lower ends, and the bending portion producesan elastic recovery force in the open state. The entire arm mayelastically deform, or only the bending portion in each arm mayelastically deform. Alternatively, each bending portion may beconfigured as a wave-shaped portion or a bellows-shaped portion. Withsuch a configuration, the portion can be expected to smoothlyelastically deform, and a sufficient elastic recovery force can beobtained.

According to another aspect of the present invention, preferably, in thesample measurement device, each of the lower ends has: a base endconnected to the lower side of the bending portion; a contact end thatcontacts the lower surface of the sample container in the closed state;a curved portion provided between the base end and the contact end thatis one of the pair of the deformation portions; and a stopper piececonnected to the contact end and that moves in an up-and-down directionalong with the contact end, the curved portion elastically deforms whenthe pressing force is applied, to lower the contact end and the stopperpiece downward, and the rack has an opening structure that allows anopening movement of the lower end when the stopper piece is at a normallevel and that collides with the stopper piece to restrict the openingmovement of the lower end when the stopper piece is at a lowered level.According to such a configuration, when no pressing force is applied,the stopper piece is at the normal level in each arm, and, in this case,the opening movement of the lower end is not restricted by the openingstructure. On the other hand, when a pressing force is applied, thestopper piece is displaced to the lowered level in each arm, and, inthis case, the opening motion of the lower end is restricted by theopening structure. According to the above-described configuration, astopper function can be realized using contact of the stopper piece tothe rack body.

According to another aspect of the present invention, preferably, in thesample measurement device, each of the lower ends has an attachmentdetachably attached to the lower side of the bending portion, and theattachment has the base end, the contact end, the curved portion, andthe stopper piece. According to this configuration, the attachment canbe replaced when the attachment is worn or degraded. According toanother aspect of the present invention, preferably, in the samplemeasurement device, a guide block is provided on a transport surface onwhich the rack is placed, and each of the lower ends has a contactmember that contacts the guide block and receives an opening force inthe horizontal direction. The contact member can be formed as a part ofthe arm body or a part of the attachment.

According to another aspect of the present invention, preferably, in thesample measurement device, the body of the rack has: a pair of upperopenings that store the pair of the bending portions of the pair of thearms; and a pair of lower openings that form the opening structure, thatallow passing of the pair of the lower ends when no pressing force isapplied, and that collide with the pair of the stopper pieces torestrict the passing of the pair of the lower ends when the pressingforce is applied. By storing the bending portion in the upper opening,even when there is a certain thickness of the bending portion,protrusion from the lateral width of the rack can be prevented in anatural state of the structure. The lower opening is an opening throughwhich the lower end passes, and an edge portion of the lower openingachieves the stopper function when a pressing force is applied.

According to another aspect of the present invention, preferably, in thesample measurement device, each of the arms has an arm body having theupper end and the bending portion, and each of the lower ends has asupport plate that is a member that extends from a lower end of the armbody in an upward direction, that contacts the lower surface of thesample container, and that deforms in a manner to fall toward an innerside in the horizontal direction by the pressing force. As a form ofeach arm body, a form may be employed in which the lower end extendsinto the inner side in the horizontal direction. It is desirable to setan elastic force of each deformation portion of the deformation memberto be weaker than an elastic force of the elastic deformation portion ofthe arm body. That is, it is desirable to configure such that adisplacement opposite to the displacement to the outer side of thehorizontal direction is caused by the pressing force.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram showing an overview of a sample measurement deviceaccording to a preferred embodiment of the present invention.

FIG. 2 is a top view of a sample measurement device.

FIG. 3 is a perspective view of a sample measurement device.

FIG. 4 is a first perspective view of a rack.

FIG. 5 is a second perspective view of a rack.

FIG. 6 is a first perspective view of a rack body.

FIG. 7 is a second perspective view of a rack body.

FIG. 8 is a first perspective view of an adapter.

FIG. 9 is a second perspective view of an adapter.

FIG. 10 is a first perspective view of an attachment.

FIG. 11 is a second perspective view of an attachment.

FIG. 12 is an explanatory diagram of an operation of an attachment.

FIG. 13 is a cross sectional diagram of a rack.

FIG. 14 is a diagram showing a non-operation state of a stopper.

FIG. 15 is a diagram showing an operation state of a stopper.

FIG. 16 is an explanatory diagram of an operation of a lower end unit.

FIG. 17 is a diagram showing an open state of an arm.

FIG. 18 is an enlarged top view of a guide block.

FIG. 19 is a cross sectional diagram of a guide block.

FIG. 20 is a perspective view showing a rack introduction state to an Xtransport path.

FIG. 21 is a perspective view showing a handing state of a samplecontainer.

FIG. 22 is an enlarged perspective view showing a handing state of asample container.

FIG. 23 is a cross sectional diagram showing a handing state of a samplecontainer.

FIG. 24 is a diagram showing an operation state of a pressing unit.

FIG. 25 is a first enlarged perspective view of a pressing unit.

FIG. 26 is a second enlarged perspective view of a pressing unit.

FIG. 27 is a diagram for explaining a function of a pressing unit.

FIG. 28 is an XZ cross sectional diagram showing a head lifted state.

FIG. 29 is an XZ cross sectional diagram showing a handing state of asample container.

FIG. 30 is an XZ cross sectional diagram showing a sample measurementstate.

FIG. 31 is a YZ cross sectional diagram showing a head lifted state.

FIG. 32 is a YZ cross sectional diagram showing a shutter operationstate.

FIG. 33 is an enlarged cross sectional diagram showing a light-shieldingstructure at a lower part of a sample measurement chamber.

FIG. 34 is a first perspective view of a shutter mechanism.

FIG. 35 is a second perspective view of a shutter mechanism.

FIG. 36 is a cross sectional diagram of a shutter mechanism.

FIG. 37 is a first perspective view showing another adapter.

FIG. 38 is a second perspective view showing another adapter.

FIG. 39 is a schematic view explaining an operation of another adapter.

FIG. 40 is a cross sectional diagram for explaining an operation ofanother adapter.

DESCRIPTION OF EMBODIMENTS

Preferred embodiments of the present invention will now be describedwith reference to the drawings.

(A) Overview of Sample Measurement Device (FIGS. 1-3)

FIG. 1 shows a sample measurement device according to a preferredembodiment of the present invention. In the present embodiment, thesample measurement device shown in FIG. 1 is a scintillation counter.The scintillation counter measures a radioactive substance contained ina sample using a liquid scintillator. Alternatively, the presentinvention can be applied to other sample measurement devices.

FIG. 1 is a schematic diagram showing an overall structure of a samplemeasurement device 10. An X direction is a first horizontal direction, aY direction is a second horizontal direction, and a Z direction is avertical direction. The sample measurement device 10 has a transporttable 12 having a transport surface extending in the X direction and theY direction. A plurality of racks 14 are transported on the transporttable 12. In the present embodiment, a Y transport path 16, an Xtransport path 20, a Y transport path 18, and another X transport pathare provided on the transport table 12. A transporting mechanism 16A isa mechanism for transporting the rack 14 in a forward direction in the Ydirection on the Y transport path 16. A transporting mechanism 18A is amechanism for transporting the rack 14 in a reverse direction in the Ydirection on the Y transport path 18. A mechanism for transporting therack 14 in the forward direction in the X direction on the X transportpath 20 is not shown in FIG. 1. Similarly, a mechanism for transportingthe rack 14 in the reverse direction in the X direction on the other Xtransport path is not shown in FIG. 1.

The rack 14 has a longitudinal direction and a short-side direction. Thelongitudinal direction is a direction of arrangement of a plurality ofstorage units 24. The short-side direction is a direction orthogonal tothe longitudinal direction. In each storage section or part 24, a samplecontainer 22 is held. The sample container 22 is, for example, a vial, atest tube, or the like. The sample container 22 includes a body 22A anda cap 22B. In the body 22A, a liquid sample 22C is stored. In the body22A, a liquid scintillator for measuring the radioactive substance inthe liquid sample is also stored. In general, the liquid scintillator isa substance that emits light upon reception of a radioactive ray (β rayin the present embodiment).

In the present embodiment, as will be described later in detail, anadaptor is mounted for each storage unit 24 on the rack body. As afunction of the adapter, an open/close mechanism 26 is realized. Thatis, the rack 14 has a plurality of open/close mechanisms 26corresponding to the plurality of storage units 24. Each open/closemechanism 26 takes a closed state and an open state. In the closedstate, the open/close mechanism 26 holds the sample container 22, and inthe open state, the holding of the sample container 22 is released andthe sample container 22 is freed. In the present embodiment, the samplecontainer 22 which is set as the measurement target is withdrawndownward from the rack 14.

A guide block 30 is fixedly placed at a location where a targetcontainer is introduced or extracted on the X transport path 20 on thetransport table 12. The guide block 30 is a member that enters a lowerpart of the rack 14. More specifically, the guide block 30 is a memberthat enters between a pair of legs of the rack 14, to apply an openingforce on each open/close mechanism 26. In addition, the guide block 30is a member that cooperates with a pressing unit 32 to be describedlater, to achieve an appropriate position and an appropriate orientationof the rack. The guide block 30 has an opening in its center,penetrating in the vertical direction. The opening corresponds to anupper end of a lifting/lowering path 28. The lifting/lowering path 28 isa passage for the sample container which is set as the measurementtarget to be lifted or lowered between the rack 14 and a samplemeasurement chamber 34. In the present embodiment, the guide block 30 ispositioned with high precision with respect to the lifting/lowering path28. In other words, as will be described later, the guide block 30 isphysically integrated to a structure that forms the lifting/loweringpath 28.

In the present embodiment, the pressing unit 32 is provided in order toachieve an appropriate position and an appropriate orientation of therack 14 during the introduction or extraction of an individual samplecontainer. The pressing unit 32 applies a pressing force on an outersurface of one leg of a pair of legs of the rack 14, to thereby cause aninner surface of the one leg to closely contact a reference surface ofthe guide block 30. With the formation of such a close contact state,the position and orientation of the rack 14 can be set appropriate.

During the sample measurement, a sample container 36 which is set as themeasurement target is stored in the sample measurement chamber 34. Alifting/lowering mechanism 40 is provided for lifting and lowering thesample container 36. With the lifting/lowering mechanism 40, the samplecontainer 36 can be moved in the up-and-down direction in thelifting/lowering path 28.

In the present embodiment, the lifting/lowering mechanism 40 has a shaft43, a head 44 provided at an upper end of the shaft 43, a slidemechanism 46 which drives the shaft 43, or the like. As will bedescribed later, in the handing of the sample container between the rack14 and the head 44, the head 44 is inserted into an opening formed inthe guide block 30. In this state, the open/close mechanism 26 providedon the storage unit 24 positioned immediately above the opening is setin the open state. More specifically, in the transport process of therack 14, the open/close mechanism 26 contacts the guide block 30, andthe open/close mechanism 26 receives an opening force in the horizontaldirection from the guide block 30 so that the open state of theopen/close mechanism 26 is formed.

The sample measurement chamber 34 is mounted on a base 48. When lightemission is caused in the sample container 36 stored in the samplemeasurement chamber 34, the light is detected by a pair ofphotomultiplier tubes 38. The pair of photomultiplier tubes 38 areprovided for executing a coincidence counting process. In the presentembodiment, a special light-shielding structure 50 is provided at alower part of the sample measurement chamber 34. With thelight-shielding structure 50, intrusion of extrinsic light through thesurface of the shaft 43 into the sample measurement chamber 34 isprevented. The light-shielding structure 50 is provided over a lowersurface of the head 44 and an upper surface of the base 48 to which thelower surface of the head 44 contacts. In the head 44 also, apredetermined light-shielding structure is provided. These elements willbe described later in detail.

In the present embodiment, the sample measurement chamber 34 is providedbelow the transport table 12. Therefore, an advantage can be obtained inthat a very heavy shielding member provided at the periphery of thesample measurement chamber 34 can be placed at a lower side of thetransport table 12. In addition, as will be described below, during thesample measurement, when extrinsic radiation is blocked and extrinsiclight is blocked at a predetermined location on the lifting/loweringpath 28, because there is no shaft 43 in this location, the extrinsicradiation and extrinsic light can be easily and reliably blocked.

Specifically, a shutter mechanism 42 is provided on the lifting/loweringpath 28, in a manner to extend across the path. The shutter mechanism 42in the present embodiment includes an upper shutter mechanism and alower shutter mechanism. That is, a double shutter mechanism isrealized. The upper shutter mechanism is a mechanism which inserts aradiation-shielding member at an upper side of the sample measurementchamber 34 to block the extrinsic radiation, and the lower shuttermechanism is a mechanism which inserts a light-shielding plate acrossthe lifting/lowering path 28 to block intrusion of extrinsic light fromabove.

In the sample measurement device 10 of the present embodiment, the rack14 is intermittently sent in the X direction on the X transport path 20and in an orientation where the longitudinal direction is coincided withthe X direction. In this case, the guide block 30 enters a lower part ofthe rack 14, and the open/close mechanisms 26 provided on the storageunits 24 are sequentially activated. The rack 14 stops in a state wherea center line of each storage unit 24 and a center line of thelifting/lowering path 28 are matched. In this state, a sample containerbefore measurement is sent from the rack 14 into the sample measurementchamber 34. After the measurement is completed, the sample container 36after measurement is returned to the original sample container storageunit. Then, with the transport of the rack 14, the open/close mechanism26 is returned from the open state to the closed state in the storageunit 24 receiving the sample container. This sequence of processes isrepeatedly executed for each storage unit 24.

FIG. 2 is a top view of the sample measurement device shown in FIG. 1.As already described, on the transport table 12, the rack 14 istransported in the horizontal direction. As the transport path of therack 14, in the present embodiment, the Y transport path 16, the Xtransport path 20, the Y transport path 18, and the X transport path 51are provided. Normally, many racks 14 are placed on the transport table12, and each rack 14 is sequentially transported on each transport path.

A center position on the X transport path 20 is a reference position forintroducing and extracting the sample container. The guide block 30 isprovided in a manner such that a center of the guide block 30 matchesthe reference position. Near the guide block 30, the pressing unit 32which realizes a pressing function to the rack 14 is provided. On the Xtransport path 20, the rack 14 is transported in the X direction by thetransporting mechanism 52 in a manner such that the longitudinaldirection of the rack 14 is parallel to the X direction. Thetransporting mechanism 52 has a hook member 54. As will be describedlater, while a tip of the hook member 54 is hooked with respect to theprotruding portion of the rack 14, the hook member 54 is moved in the Xdirection. With this process, the rack 14 is transported in the Xdirection. The hook member 54 is configured so as not to obstructoperations of the open/close mechanisms even in a state where the tipportion thereof is engaged with respect to the rack 14.

In the X transport path 50 at the opposite side also, a transportingmechanism 56 for transporting the rack 14 in the X direction isprovided. The transporting mechanism 56 basically has the same structureas the transporting mechanism 52. On the X transport path 50, no membercorresponding to the guide block 30 is provided, but a pressing unithaving the same structure as the pressing unit 32 is placed.

FIG. 3 is a perspective view showing a part of the transport table. Asdescribed above, on the Y transport path 16, the rack 14 is transportedin the Y direction. In this case, the rack 14 is translated in a mannersuch that the short-side direction of the rack 14 is directed to the Ydirection. On the X transport path 20, the rack 14 is transported in amanner such that the longitudinal direction of the rack 14 is directedto the X direction. In order to strictly match the longitudinaldirection of the rack 14 with the X direction during introduction andextraction of the sample container, the pressing unit 32 described abovepresses one leg of the rack 14 toward the side of the guide block 30.

The guide block 30 is provided on the reference position on the Xtransport path 20. In FIG. 3, a head which is a part of thelifting/lowering mechanism is entered in the opening of the guide block30. That is, in FIG. 3, the head is in a lifted state. As describedabove, the transporting mechanism 52 has the hook member 54.

(B) Rack and Adapter (FIGS. 4-17)

Next, the rack and the adapter will be described in detail.

FIG. 4 is a perspective view showing the rack 14 viewed from diagonallyabove. The rack 14 holds a plurality of sample containers arranged inthe longitudinal direction (X direction in FIG. 4). The rack 14 includesa rack body 58, and a plurality of adapters 60 detachably attached tothe rack body 58. A plurality of storage units 24 are provided in therack 14, and the adapter 60 is provided for each storage unit 24. Aswill be described later in detail, the adapter 60 includes a ring-shapedframe 66, and a pair of arms 70 and 72 extending from the ring-shapedframe 66 in the downward direction. The arm 70 and the arm 72 as a wholeform the open/close mechanism described above.

The rack 14 has a pair of legs 64A and 64B distanced from each other inthe short-side direction. Each of the legs 64A and 64B extends in thelongitudinal direction. A region between the pair of legs 64A and 64Bforms a cavity section for allowing the guide block to pass. A frontside and a rear side of the cavity section are both openings. On a frontend of the rack 14, a protrusion portion 58A is provided. The tip of thehook member is inserted into the rack opening of the protrusion portion58A. Alternatively, a rack may be used in which, in addition to thelongitudinal direction, a plurality of storage units are arranged in theshort-side direction.

FIG. 5 is a perspective view of the rack 14, viewed from diagonallybelow. As described above, the rack body has the pair of legs 64A and64B. The adapter 60 has the ring-shaped frame 66 and the pair of arms 70and 72 placed in a distanced manner from each other in the short-sidedirection. The pair of arms 70 and 72 have a pair of lower endstructures 74 and 76, which form a primary portion of the open/closemechanism 26.

FIG. 6 shows the rack body 58 viewed from diagonally above. The rackbody 58 has a plurality of storage holes 24A arranged in thelongitudinal direction. In each storage hole 24A, a one-side surfacestructure and an other-side surface structure are provided on both sidesin the short-side direction. Because these structures have a symmetricshape, the one-side surface structure will be described as arepresentative of these two structures. A side plate 78 extending in thevertical direction is provided on one side of the storage hole 24A. Arib formed as a thick portion is provided between two adjacent sideplates 78 or over the two adjacent side plates 78. A substantial portionof the side plate 78 is formed as a thin portion. At an upper part ofthe side plate 78, an upper opening 82 is provided, and, at a lower partof the side plate 78, a lower opening 84 is formed. The upper opening 82and the lower opening 84 are each an opening penetrating in theshort-side direction. FIG. 7 shows the rack body 58 viewed fromdiagonally below.

Next, a structure and a function of the adapter will be described withreference to FIGS. 8-17.

FIG. 8 shows the adapter 60 viewed from diagonally above. As describedabove, the adapter 60 has the ring-shaped frame 66 and the pair of arms70 and 72 extending from the ring-shaped frame 66 in the downwarddirection. The ring-shaped frame 66 has a ring shape corresponding tothe storage hole, and has a rib or the like. The pair of arms 70 and 72are distanced from each other in the short-side direction (Y directionin FIG. 8), and the sample container is maintained between the arms. Thearm 70 and the arm 72 have a form symmetric with each other. Here, thearm 72 will be described. The arm 72 has an upper portion 86 connectedto the ring-shaped frame 66, a wave-shaped portion 88 serving as abending portion provided at a lower side of the upper end portion 86,and a lower end portion 90 provided at a lower side of the wave-shapedportion 88. The lower end portion 90 has a hook portion 92 which is bentin the inner side. An attachment to be described later is attached oneach hook portion 92 of the two arms 70 and 72, and two lower endstructures 74 and 76 to be described later in detail are thus formed.The wave-shaped portion 88 has a bellows form. When an opening force toan outer side in the horizontal direction is applied on the hook portion92, the arm 70 is bent about the wave-shaped portion 88 by this force.At the same time, the arm 72 is similarly deformed. With this process,the two arms 70 and 72 are set in a state where the arms are opened inthe short-side direction. The wave-shaped portion 88 is formed as anelastic portion. Because an elastic recovery force is achieved by theelastic portion, when the opening force in the horizontal directionstops acting on the two arms 70 and 72, the two arms 70 and 72 arereturned to their original shapes by the above-described elasticrecovery force. In other words, the two arms 70 and 72 are set in theclosed state.

FIG. 9 shows the adapter viewed from diagonally below. As describedabove, the adapter 60 has the two arms 70 and 72, each of which has thehook portion 92. In the present embodiment, the hook portion 92 has ahook base 92A which is a bent portion and which forms a base surface.The hook base 92A has a U shape when viewed from the above. In the hookbase 92A, a contact member 92D extending in the vertical direction isprovided. The contact member 92D has a semi-cylindrical shape or a Dshape when viewed from above. When the contact member 92D contacts aninclined surface formed in the guide block during a movement of therack, an opening force is generated toward the outer side in thehorizontal direction. A connector 92E is provided below the hook base92A, and is fixed on the contact member 92D. The connector 92E has arectangular shape, and an attachment is detachably attached using theconnector 92E. On lower end portions of the arms 70 and 72, an L-shapedchannel 92F having an L shape when viewed in the X direction is formed.

FIG. 10 is a first perspective view of the attachment attached to thebody of the adapter. FIG. 10 shows the attachment 96 viewed fromdiagonally above.

As shown in FIG. 10, the attachment 96 has a connection structure 98which is connected to the hook portion shown in FIGS. 8 and 9. Theconnection structure 98 forms a connection end, and more specificallyhas a lower plate 106 and an upper plate 108. The region between theplates is a slit 110, and the connector shown in FIG. 9 is inserted intothe slit 110. In FIG. 10, in the slit 110, a protrusion (not shown) isprovided, and the protrusion is fitted into an opening formed in theconnector. With this process, the attachment 96 is mounted on the bodyof the adapter.

A seat plate 102 serving as a movable piece is provided above theconnection structure 98. The seat plate 102 forms a contact end, and anupper surface thereof functions as a seat surface. That is, a lowersurface of the sample container is placed on the seat plate 102.

A C-shaped arm 100 having a C shape is provided between the connectionstructure 98 and the seat plate 102. The C-shaped arm 100 functions asan elastic deformation section. In a natural state, the seat plate 102is in an inclined orientation. When a pressing force is applied on theseat plate 102 from above through the sample container, the C-shaped armis elastically deformed to absorb the pressing force. In this state, theseat plate 102 is set in a horizontal orientation.

On a right end and a left end of the seat plate 102, a pair of stopperpieces 104A and 104B extending downward are provided. With anup-and-down movement of the seat plate 102, the pair of stopper pieces104A and 104B also move in the up-and-down direction. Thus, when theseat plate 102 is lowered in the downward direction, the stopper pieces104A and 104B also are moved in the downward direction, and the lowerend positions thereof are further lowered. As a result, as will bedescribed later, even if the lower end structure attempts to move towardthe outer side in the horizontal direction, the stopper pieces 104A and104B collide with the adapter body, and the opening movement of thelower end structure is blocked.

FIG. 11 is a second perspective view of the attachment 96. Specifically,FIG. 11 shows the attachment 96 viewed from diagonally below. Asdescribed above, the attachment 96 has the connection structure 98, theC-shaped arm 100, and the seat plate 102. On the right end and the leftend of the seat plate 102, the pair of stopper pieces 104A and 104B areprovided. Alternatively, the body of the adapter and the attachment maybe integrally formed.

The function of the adapter will now be described with reference toFIGS. 12-17. FIG. 12 is an explanatory diagram for explaining anoperation of the adapter. The adapter is attached to the rack body. Arms70 and 72 have lower end structures 74 and 76. Each of the lower endstructures 74 and 76 has the attachment 96. In FIG. 12, an attachment inan inclined orientation before deformation is shown with a referencenumeral 96A, and an attachment in a horizontal orientation after thedeformation is shown with a reference numeral 96B.

In a state where the sample container is lowered into the storage unit,the seat plates of the pair of attachments contact the lower surface ofthe sample container. With this configuration, the sample container issupported from below. In this case, as shown with the reference numeral96A, the seat plates of the attachments are in a lifted state, and twoarms are in the closed state.

In the closed state, when an excessive pressing force 111 is appliedfrom above toward below with respect to the sample container, theattachment is deformed as shown with the reference numeral 96B, by thepressing force 111. Specifically, the seat plate in each attachment islowered downward and is set in the horizontal orientation. At the sametime, the stopper pieces 104A and 104B attached to the seat plate aremoved downward. On the other hand, due to the pressing force from above,the two arms 70 and 72 attempt to move in a direction away from eachother; that is, the opening direction (refer to reference numeral 112).However, because the stopper pieces 104A and 104B are lowered downwardalong with the seat plate, even when the lower end structures 74 and 76attempt to pass the lower opening formed in the rack body and move tothe outside, the stoppers 104A and 104B collide with the inner surfacesof the legs 64A and 64B, blocking such an opening movement 112. In otherwords, in the opening movement by the pressing force, the lower endstructures 74 and 76 do not protrude to the outside of the rack bodythrough the lower opening, and the holding of the sample container ismaintained. While the sample container stores the liquid sampleincluding a radioactive substance, falling of such a sample containerfrom the rack can be reliably prevented.

On the other hand, when the pressing force 111 is not present, only theforce due to the weight of the sample container is applied to theattachment. In this case, as shown with the reference numeral 96A, ineach attachment, the seat plate maintains the lifted orientation. Insuch a case, the lower end positions of the stopper pieces 104A and 104Bare at the lifted end, and thus, when an opening force to the outer sidein the horizontal direction is applied to the lower end structures 74and 76, protrusion of the lower end structures 74 and 76 to the outsideof the rack body through the lower opening formed in the rack body ispermitted. In other words, in the pair of the arms, deformation from theclosed state to the open state is permitted.

As described, according to the present embodiment, the protrusion of thelower end structures 74 and 76 to the outside of the rack body ispermitted only when an appropriate force to the outer side in thehorizontal direction is applied from the guide block. When an abnormalforce is caused in the vertical direction, the change of the pair of thearms from the closed state to the open state can be prevented by thefunctions of the stopper pieces 104A and 104B.

FIG. 13 is a cross sectional diagram of the rack. Specifically, FIG. 13shows a state where the adapter is attached to the rack body. In thearms 70 and 72, a part of the wave-shaped portion 88 is stored in theupper opening shown with R1. The entirety of the arms 70 and 72 issubstantially stored in a thick thickness D1 of the rack body, exceptfor the lower end structures 74 and 76. Thus, in the state before thedeformation of the arms 70 and 72, no portion in the arms 70 and 72protrudes from the rack body toward the outer side. With thisconfiguration, even when a specific rack is moved in the longitudinaldirection in an aligned state of a plurality of the racks, no hookingoccurs that would block the movement.

In a normal closed state where no pressing force from above is applied,when an opening force shown with a reference numeral 114 is applied tothe lower end structures 74 and 76 by the contact with the guide block,the lower end structures 74 and 76 move in a direction away from eachother, and protrude toward the outer side of the rack through the pairof lower openings.

In FIG. 13, R3 shows a size in the vertical direction of the loweropening 84. R2 shows a size in the vertical direction of a main regionof the lower opening 84, and R4 shows a size in the vertical directionof a sub area of the lower opening. When the opening force 114 isapplied in the closed state, the lower end structures 74 and 76 passthrough the pair of lower openings. On the other hand, when the pressingforce from above is caused, the plurality of stopper pieces are lowereddownward, and, even when the lower end structures 74 and 76 attempt tomove in a direction away from each other, the plurality of stopperpieces collide with the inner surfaces of the pair of legs, and such anopening movement is blocked. This operation will now be furtherdescribed with reference to FIGS. 14 and 15.

FIG. 14 shows a state where the stopper piece is not operating. In sucha case, in the lower end structure 76, the stopper pieces 104A and 104Bare in the lifted position, and there is a gap h1 between a lower sidelevel of the main area in the lower opening 84 and the lower end levelsof the stopper pieces 104A and 104B. Therefore, the lower end structure76 can protrude to the outside through the lower opening 84.

In the contrary, FIG. 15 shows an operation state of the stopper piece.Specifically, when the pressing force 114 is applied to the lower endstructure 76, the stopper pieces 104A and 104B are lowered downward, andthe lower end levels thereof become further lower than the lower sidelevel of the main area of the lower opening 84. An overlapped portion inthis process is shown in FIG. 15 with Δh. In this state, even when thelower end structure 76 attempts to protrude to the outside through thelower opening 84, the stopper pieces 104A and 104B collide with theinner sides of the leg 64B, and the movement is reliably prevented.

FIG. 16 shows a state where the sample container 22 is stored in therack. Part (A) shows a normal state and part (B) shows a state where thepressing force is caused. Reference numerals 74A and 76A show the lowerend structures before deformation and in the lifted state, and referencenumerals 74B and 76B show the lower end structures after deformation andin the lowered state.

FIG. 17 shows an open state of the arm 72. With the movement of the rackin the X direction and contact with the guide block, an opening force116 in the horizontal direction is applied on the lower end structure.With this process, as described above, the entirety of the arm 72including the lower end structure is moved in an open movement. Thelower end structure in the open state is shown with a reference numeral76C. In this case, the arm 72 is bent and deformed about the wave-shapedportion in the arm 72. An amount of protrusion of the overall arm 72from the side surface of the rack is shown by a reference numeral 118.In such an open state, because the supporting function with respect tothe lower surface of the sample container 22 disappears, if there is nomember below the sample container 22, the sample container 22 naturallyfalls below as shown by a reference numeral 120. In the presentembodiment, in such an open state, the sample container 22 is placed onthe head.

When the sample container is moved from the rack to the head, the pairof lower end structures is moved from a position immediately below thesample container to a retracted position in an outer side in thehorizontal direction. Then, after the sample container after the samplemeasurement is returned to the inside of the sample storage unit, thepair of the arms is returned to the original shape. That is, the pair oflower end structures enter the lower side of the sample container. Withthis configuration, the sample container 22 is supported by the pair ofthe lower end structures, and is held.

As described, according to the present embodiment, in each storage unit,the open/close mechanism can be transitioned from the closed state tothe open state at an appropriate timing. In addition, when an abnormalpressing force in the vertical direction is caused in place of theappropriate opening force, unnecessary opening movement is reliablyprevented by the function of the plurality of stopper pieces asdescribed above. With such a configuration, falling of the samplecontainer can be prevented beforehand. Further, an elastic deformationsection is provided in each arm, and, with the elastic recovery forceachieved thereby, the arm can be returned to its original shape.Therefore, the transition from the open state to the closed state can beachieved by the function of the arm itself. According to the presentembodiment, no dedicated drive source and no dedicated controller arenecessary for the opening operation of the pair of the arms. Inaddition, no dedicated drive source and no dedicated controller arenecessary for the closing operation of the pair of the arms. The pair ofthe arms can be opened and closed using a part of the transporting forceof the rack and in synchronization with the transportation of the rack.

(C) Guide Block (FIGS. 18-23)

FIG. 18 shows a part of the transport table as an enlarged top view.Specifically, FIG. 18 shows the guide block 30 and the pressing unit 32.

The guide block 30 is fixedly placed on a top frame 122. The top frame122 corresponds to a top plate of a structure including thelifting/lowering path. The guide block 30 has a lower layer 124, anupper layer 126, a front-side support plate 130, and a rear-side supportplate 132. These elements are integrated. Each of the lower layer 124and the upper layer 126 has a flat plate shape spreading in thehorizontal direction. The front-side support plate 130 and the rear-sidesupport plate 132 have a form standing upwards. At the center of theguide block 30, an opening 128 is formed. The opening 128 has a circularor elliptical shape. The opening 128 forms an upper end of thelifting/lowering path, and, in FIG. 18, the head 44 is inserted into theopening 128. A width W1 in the Y direction of the lower layer 124 isapproximately the same as a gap between the pair of legs of the rack.Strictly speaking, the width W1 is slightly smaller than the gap. Oneach of a front end portion (left end portion in FIG. 18) and a rear endportion (right end portion in FIG. 18) of the lower layer 124, a pair ofinclined surfaces 134 are formed. In other words, the lower layer 124has a shape tapered in both directions. A width in the Y direction of afront surface and a rear surface of the lower layer 124 is W2, andW1>W2. Because the pair of inclined surfaces 134 are formed on the frontend portion in this manner, even if there is a position deviation in theY direction for the rack side in the process of entry of the guide block30 into a region between the pair of legs, the position deviation can beresolved. In addition, a pair of inclined surfaces are also formed onthe rear end portion of the lower layer 124. With such a configuration,even if it becomes necessary to return-transport the rack, the guideblock 30 can be smoothly inserted into the lower part of the rack fromthe rear side of the rack.

The upper layer 126 is a portion layered on top of the lower layer 124,and a pair of inclined surfaces 136 are formed with a relatively longdistance at a front-side portion of the upper layer 126. A width in theY direction of the front end surface in the upper layer 126 is W3. Here,W1>W2>W3. The pair of inclined surfaces 136 are provided such that thewidth in the Y direction of the upper layer 126 continuously changesfrom W3 to W1 along the X direction.

When the pair of contact members of the pair of open/close mechanismscontacts the pair of inclined surfaces 136, and the rack is movedforward while the contact state is maintained, an opening force to theouter side in the horizontal direction is applied on the pair of contactmembers by the function of the pair of inclined surfaces 136. With thisprocess, the adapter is changed from the closed state to the open state.In the present embodiment, a pair of inclined surfaces are also formedon the rear-side portion of the upper layer 126. With the pair of theinclined surfaces on the rear side, the recovery from the open state tothe closed state can be gradually achieved, thus preventing a rapidchange of the open/close mechanism.

In the present embodiment, the pair of inclined surfaces 136 on thefront side and the pair of inclined surfaces on the rear side formed onthe upper layer 126 have a symmetrical shape, but alternatively, thesesurfaces may have an asymmetrical shape.

The guide block 30 can be roughly divided from the upstream side to thedownstream side of the X direction, into a front-side form, anintermediate form, and a rear-side form. Looking into the upper layer126, the front-side form of the upper layer 126 realizes the function tochange the open/close mechanism from the closed state to the open state.The intermediate form of the upper layer 126 realizes a function tomaintain the open state. The rear-side form of the upper layer 126realizes a function to return the open/close mechanism from the openstate to the closed state. The guide block 30 as a whole has asymmetrical shape with reference to a center line passing through acenter position in the Y direction and parallel to the X direction. In astate where the guide block 30 enters a region between the pair of legsof the rack, centering (positioning in the Y direction) of the rack isexecuted. With this process, the center position of the opening 128 andthe center position of the sample container to be measured or a samplestorage unit that stores the sample container can be easily matched inthe Y direction.

In the present embodiment, as described above, the guide block 30 isfixed on the top frame 122 of the structure including the samplemeasurement chamber and the lifting/lowering mechanism. The guide block30 is placed with a certain degree of freedom in the horizontaldirection with respect to the transport table. In other words, so longas the guide block 30 is appropriately positioned, it becomesunnecessary to strictly position the transport table itself. Forexample, even if there is a machining error or an assembly error in thetransport table, if the error is within an allowable range, such anerror would not cause a problem in the handing of the sample containerbetween the rack and the lifting/lowering mechanism.

In the process of change of the open/close mechanism from the closedstate to the open state with the function of the pair of inclinedsurfaces 136 formed on the front side of the guide block, the supportingfunction of the sample container by the open/close mechanism disappears.If the support function disappears before the bottom surface of thesample container is sufficiently placed on the head 44, there is apossibility of fall-off or change of orientation of the samplecontainer. In consideration of this, in the guide block 30 according tothe present embodiment, the front-side support plate 130 is provided.The front-side support plate 130 has a form protruding upward from theupper surface of the upper layer 126. The front-side support plate 130realizes a function to support the sample container temporarily and inan auxiliary manner in a state where the supporting function of thesample container by the open/close mechanism has disappeared. A frontend and a rear end of the front-side support plate have tapered surfacesof a shoulder shape, such that hooking of a corner portion of the samplecontainer on the front-side support plate is prevented. By preparing anauxiliary support on the front side of the opening 128 in this manner,it becomes possible to prevent fall-off or orientation change of thesample container, and to smoothly transfer the sample container from therack to the upper surface of the head.

In the present embodiment, the rear-side support plate 132 is providedon the rear side of the opening 128. The rear-side support plate 132 hasa form similar to that of the front-side support plate 130. With therear-side support plate 132, in a case where, after the sample containerafter the measurement is returned to the storage unit and in a perioduntil the open/close mechanism returns from the open state to the closedstate, if the support function by the upper surface of the head 44partially disappears, the sample container can be temporarily supportedin an auxiliary manner by the upper surface of the rear-side supportplate 132, to prevent fall-off and orientation change of the samplecontainer.

As described, according to the guide block 30 of the present embodiment,an opening force to the outer side in the horizontal direction can beapplied to each open/close mechanism using a part of the racktransporting force. Therefore, because it is not necessary to provide adedicated drive source or a dedicated drive mechanism for producing suchan opening force, there is an advantage that the device structure can besimplified. In addition, the operation timing of each open/closemechanism can be naturally matched with respect to a reference position,and there is an advantage that it is not necessary to control theopening/closing by a controller. Furthermore, because the guide block 30is placed with reference to the reference position itself, the rack canbe centered merely by inserting the guide block 30 between the pair ofthe legs of the rack. In other words, the sample container or thestorage unit having the sample container can be appropriately positionedwith respect to the reference position by merely inserting the guideblock 30 to the lower part of the rack.

FIG. 18 also shows the pressing unit 32 in addition to the guide block30. A structure of the pressing unit 32 will now be described. Thestructure and an operation of the pressing unit 32 will again describedlater with reference to FIGS. 24-26.

In FIG. 18, the pressing unit 32 is a unit which applies a pressingforce on the rack from the outside of the rack, to realize appropriateposition and orientation of the rack. In the present embodiment, thepressing unit 32 has a pair of rollers 138 and 140 which contact therack and apply the pressing force. A rotational center of the roller 138is set at a point distanced from the reference position 143 by a certaindistance 144 in the upstream side; that is, the front side, in the Xdirection. A rotational center of the roller 140 is set at a pointdistanced from the reference position 143 by the certain distance 144 inthe X direction.

As will be described later, the roller 138 is rotatably attached on anend of one movable plate, and the roller 140 is attached to an end ofthe other movable plate. A common rotational axis of the movable platesis shown with a reference numeral 142. In the Y direction, therotational centers of the rollers 138 and 140 are set farther away fromthe guide block 30 with respect to a rotational center of the commonrotational axis 142. In other words, a negative offset is given to therotational centers.

Reference surfaces are formed in the guide block 30 for cooperation withthe pressing unit 32 to achieve appropriate position and orientation ofthe rack. Specifically, reference surfaces 124A and 126A are formed. Thereference surface 124A is one side surface of the lower layer 124 andthe reference surface 126A is one side surface of the upper layer 126.In the present embodiment, the reference surfaces 124A and 126A aresurfaces parallel in the X direction, and are vertical surfaces. Of thetwo reference surfaces 124A and 126A, the reference surface 124A spreadswider in the X direction. When the guide block enters a region betweenthe pair of legs of the rack, the pair of rollers 138 and 140 arepressed against the outer surface of one leg (leg on the side of thepressing unit 32) of the pair of legs. With this process, the innersurface of the one leg closely contacts the reference surfaces 124A and126A. The reference surfaces are vertical surfaces parallel in the Xdirection, and the inner surfaces of the pair of legs are verticalsurfaces parallel in the longitudinal direction. Thus, in a state wherethe inner surface is in close contact with the reference surface, the Xdirection and the longitudinal direction of the rack become parallel toeach other. At the same time, the rack is positioned at a predeterminedposition in the Y direction. As a result, appropriate position andorientation of the rack can be realized.

In the present embodiment, in an initial state of the rollers 138 and140, there is a certain gap ΔW between the respective roller and thereference surfaced 124A. Such a gap ΔW is provided as necessary. In thepresent embodiment, with the gap ΔW and the negative offset of theroller 138, an angle θ1 for receiving a tip portion of one leg isincreased, or a resistance when the tip portion is received is reduced.With the function of the inclined surface 134 and such an open angle θ1,even if there is a position deviation in the Y direction in the rack,the one leg can be smoothly inserted between the reference surface 124Aand the roller 138.

In a state where the guide block 30 is inserted between the pair of legsas described above, a pressing force is applied from the rollers 138 and140 on the outer surface of the one leg. With this process, the innersurface of the one leg closely contacts the reference surfaces 124A and126A. Therefore, an appropriate position (in particular, a position inthe Y direction) and an appropriate orientation of the rack can beachieved with a simple mechanism. In the present embodiment, because therollers 138 and 140 are provided as the pressing member, even when therack is sent toward the front side, a sliding resistance can be reduced.

In the present embodiment, the pressing unit 32 presses the rack withrespect to the guide block 30 placed at the appropriate position andorientation. Thus, even if there is a machining error or an assemblyerror in the transport table, the rack can be accurately positioned withrespect to the reference position. In addition, in the presentembodiment, the rollers 138 and 140 are provided with an equal spacingin the front-and-rear direction from the reference position in the Xdirection. Therefore, a force can be equally applied on both sides ofthe reference position on the rack. Even if there is a deflection in therack, in the present embodiment, the pressing is applied in a range inthe X direction where the guide block 30 exists, and thus, even with thedeflection, the sample container to be measured can be appropriatelypositioned with respect to the reference position.

A description of a function of the guide block will be continued withreference to FIGS. 19-23.

FIG. 19 shows a cross sectional diagram of the guide block 30. Asdescribed above, the guide block 30 has the upper layer 124, the lowerlayer 126, the front-side support plate 130, and the rear-side supportplate 132. In FIG. 19, each member is shown as a separate member, but inthe present embodiment, the members are integrated. The front-sidesupport plate 130 has an upper surface 130B, and inclined surfaces 130Aand 130C provided in front of and to the rear of the upper surface 130B.The rear-side support plate 132 has a structure similar to that of thefront-side support plate 130.

The opening 128 penetrating through the guide block 30 in theup-and-down direction is formed at a center of the guide block 30. InFIG. 19, the head 44 is inserted into the opening 128. The head 44 has aplacement surface 44A serving as an upper surface, and the samplecontainer 22 is placed on the placement surface 44A. As shown in FIG.19, in the process of transition from the closed state to the open stateof the open/close mechanism, the sample container 22 is supported in anauxiliary manner by the upper surface 130B of the front-side supportplate 130. As a result, the sample container 22 can be smoothlytransferred onto the placement surface 44A. During the transfer, it isdesirable that a level of the placement surface 44A of the head 44 and alevel of the upper surface 130A are substantially matched.Alternatively, one of these surfaces may be slightly above or below theother surface.

FIG. 20 shows a state where the rack 14 is introduced to the X transportpath. As described above, the rack 14 has the protrusion 58A, and a partof the hook member 54 of the transporting mechanism 52 is inserted tothe protrusion 58A. The guide block 30 is provided at the center of theX transport path, and the pressing unit 32 is provided nearby.

FIG. 21 shows a state where the rack 14 is progressed on the X transportpath. Specifically, FIG. 21 shows a state where the front-most samplecontainer is positioned with respect to the opening of the guide block30. In this state, the pressing unit 32 functions, and an appropriateposition and an appropriate orientation of the rack 14 are realized.

FIG. 22 shows a part of the contents shown in FIG. 21 as an enlargedview. The rack 14 has a plurality of storage units, and the adapter 60is attached in each storage unit. The adapter 60 has the open/closemechanism 26. In FIG. 22, only one open/close mechanism 26 is set in theopen state. The guide block 30 functions to form such an open state. Asdescribed above, the guide block 30 has the lower layer 124, the upperlayer 126, etc. The guide block 30 is inserted between the pair of legsin the rack 14. In FIG. 22, only the leg 64B on the other side is shown.On the rear side of the lower layer 124, the pair of inclined surfaces134 is formed, and on the rear side of the upper layer 126, the pair ofinclined surfaces 136 is formed. In the front-side portions of the lowerlayer 124 and the upper layer 126 also, the pair of inclined surfacesare formed. In the state shown in FIG. 22, the pressing force in the Ydirection is applied on the rack by the pressing unit 34, so that theappropriate position and orientation of the rack 14 are achieved andstabilized.

FIG. 23 is a YZ cross sectional diagram of a portion shown in FIG. 22.FIG. 23 includes a cross section of the guide block 30. As describedabove, in the rack 14, the adapter 60 is provided in each storage unit,and the sample container 22 is stored inside the storage unit. In thestate shown in FIG. 23, the open/close mechanism 26 is in the openstate, and thus, the lower end structures 74 and 76 protrude from therack body in both sides in the horizontal direction. Such a function iscaused by the pair of contact members of the lower end structures 74 and76 contacting the pair of inclined surfaces of the guide block 30.

In FIG. 23, a pressing force is applied from the pressing unit 32 to therack 14 such that the position and orientation of the rack 14 arestabilized. The lifting/lowering path 28 is formed on the lower side ofthe guide block 30. As already described, the lifting/lowering mechanismhas the shaft 43 and the head 44. These elements move in the up-and-downdirection inside the lifting/lowering path 28.

As shown in FIG. 23, the shutter mechanism 42 is provided below theguide block 30 across the lifting/lowering path 28. The shuttermechanism 42 will now be briefly described. The shutter mechanism willbe again described later with reference to FIGS. 34-36.

The shutter mechanism 42 includes an upper shutter mechanism 42A and alower shutter mechanism 42B. The upper shutter mechanism 42A is amechanism for blocking extrinsic radiation from above, and the lowershutter mechanism 42B is a mechanism for blocking extrinsic lightentering through the lifting/lowering path 28.

Specifically, the upper shutter mechanism 42A has a lead block 148. Withthe lead block 148 covering the upper side of the sample measurementchamber across the lifting/lowering path 28, the extrinsic radiation (inparticular, cosmic rays or the like) directed toward the samplemeasurement chamber through the lifting/lowering path 28 is blocked.Portions of the sample measurement chamber other than thelifting/lowering path 28 are basically covered with a shielding member.Alternatively, when the blockage of the space ray is the objective, theplacement of the shielding member on the lower side of the samplemeasurement chamber may be omitted.

The upper shutter mechanism 42A has a tube guide 146. The tube guide 146is positioned on the lifting/lowering path 28 when the lead block 148 isin the retracted position, and realizes a guide function with respect tothe head 44 and the sample container 22 in this state. In the statewhere the lead block 148 is moved forward, the tube guide 146 moves to aposition retracted from the lifting/lowering path 28. The tube guide 146is a hollow member similar to a sleeve, and has an alignment function aswill be described later.

The lower shutter mechanism 42B has a light-shielding plate 150 and aslit structure 230. When the light-shielding plate 150 is moved forward,a part of the light-shielding plate 150 is inserted into a slit of theslit structure 230, and, with this process, the light-shielding plate150 is placed across the lifting/lowering path 28. In this state, theextrinsic light from above is blocked by the light-shielding plate 150.

As described, according to the guide block, the open/close mechanism canbe opened using a part of the drive force for transporting the rack inthe X direction. Therefore, there is an advantage that it is notnecessary to provide a dedicated drive source for such an openingoperation. In addition, when the guide block is inserted between thepair of legs, an appropriate position of the rack in the Y direction canbe achieved. That is, the centering can be realized naturally. Inaddition, because the guide block of the present embodiment has a memberwhich supports in an auxiliary manner the lower side of the samplecontainer in a halfway state between the open state and the closedstate, it is possible to prevent disturbance in the orientation or thelike of the sample container during the operation of the open/closemechanism. Further, the guide block 30 of the present embodiment has thereference surface which functions with the pressing unit, and, with thecooperation of these elements, the appropriate position and orientationof the rack can be easily realized.

(D) Pressing Unit (FIGS. 24-27)

FIG. 24 shows an operation state of the pressing unit 32 as aperspective view. When the rack 14 is transported in the X direction,the pressing unit 32 realizes its function on the left side in thedirection of movement of the rack 14. As described above, the pressingunit 32 has the pair of rollers 138 and 140. In order to give an elasticurging force to the pair of rollers, a first movable plate 154 and asecond movable plate 156 are provided.

FIG. 25 is a first perspective view of the pressing unit. The firstmovable plate 154 is an upper plate, and the second movable plate 156 isa lower plate. The plates 154 and 156 rotate about the common rotationalaxis 142. The first movable plate 154 has a crank shape and the secondmovable plate 156 also has a crank shape.

The first movable plate 154 has a front-side bent portion 154 a, anintermediate portion 154 b, and a rear-side bent portion 154 c. Theroller 138 is rotatably attached to an end of the front-side bentportion 154 a. The second movable plate 156 has a front-side bentportion 156 a, an intermediate portion 156 b, and a rear-side bentportion 156 c. The roller 140 is rotatably provided on an end of thefront-side bent portion 156 a. A pin 160 is a restriction member forpreventing unnecessary excessive rotation of the first movable plate 154in a counterclockwise direction as viewed from above. Similarly, a pin158 is a restriction member for preventing unnecessary excessiverotation of the second movable plate 156 in the clockwise direction asviewed from above.

FIG. 26 is a second perspective view of the pressing unit. As describedabove, the first movable plate 154 has the rear-side bent portion 154 c,and a movement axis 164 is provided at an end thereof. The secondmovable plate 156 has the rear-side bent portion 156 c, and a movementaxis 166 is provided at an end thereof. A spring 162 is provided in astate of being extending more than in the natural state, between themovement axis 164 and the movement axis 166. In other words, an elasticrecovery force is caused at all times in the spring 162, which istransmitted to the pair of rollers 138 and 140 through the first movableplate 154 and the second movable plate 156. With this configuration, thepressing force to the rack is produced. However, as described above, therotational angles of the plates 154 and 156 in the initial state arerestricted by the pair of restriction pins. With this configuration, thegap ΔW shown in FIG. 18 is set.

FIG. 27 is a diagram showing a function of the pressing unit. A negativeoffset 168 is set for the centers of rotation of the rollers 138 and 140with respect to the center of the common rotational axis 142. That is,the centers of rotation of the rollers 138 and 140 are shifted in the Ydirection in a direction farther away from the guide block, relative tothe center of the rotational axis 142. The spring 162 is placed betweenthe first movable plate 154 and the second movable plate 156, and, whenthe rollers 138 and 140 move in a direction away from the guide block,the spring is extended, and a stronger elastic urging force is producedas a reaction force. With this configuration, the pressing force 172which presses the rollers 138 and 140 toward the side of the rack isproduced.

In the present embodiment, because the spring 162 is placed between thetwo movable plates, in the state where the leg is entered only in theregion between the roller 138 and the reference surface, a weak pressingforce F1 can be produced, and when the legs are entered in the regionsbetween the two rollers 138 and 140 and the reference surface, a strongpressing force F2 which is a sum of the forces for the two rollers 138and 140 can be produced. In other words, a gradational force can berealized according to the situation of the entrance. In the initialstate where the leg is not entered between the roller 138 and thereference surface, a gap ΔW is formed in the region, and thus, the forceapplied on the leg when the leg enters the region (reaction force,impact force) can be reduced as compared to a case where the gap is notformed.

According to the pressing unit as described above, as described withreference to FIG. 18, the pressing force can be applied to the outersurface of one leg so that the inner surface of the one leg is in closecontact with the reference surface of the guide block. In addition, inthis case, because the rollers 138 and 140 are placed to have thenegative offset 168, as shown in FIG. 18, an advantage can be obtainedin which the open angle for receiving the one leg can be set relativelylarge. In other words, the rotational movement of the first movableplate can be executed smoothly. Moreover, because in the presentembodiment the spring is placed between the two movable plates, thepressing force can be gradationally increased according to the state ofsandwiching.

(E) Structure of Lower Side of Transport Surface (FIGS. 28-33)

Next, a structure of a lower side of the transport surface will bedescribed. FIG. 28 shows a state where the rack 14 is introduced in theX transport path. In this state, the head 44 is inserted into theopening of the guide block 30. That is, the head 44 is at the uppermostposition. The sample measurement chamber 34 is provided immediatelybelow the opening, and a pair of photomultiplier tubes 174 and 176forming the measurement unit are provided on respective sides of thesample measurement chamber 34. A shielding structure 178 is provided ina manner to wrap the entirety of the sample measurement chamber 34 andthe pair of photomultiplier tubes 174 and 176. The shielding structure178 is formed from lead or the like, and blocks radiation reaching fromthe outside. However, shielding in the lifting/lowering path is executedby the shutter mechanism to be described later.

FIG. 29 shows a state where a front-most sample container 36 is movedonto the head 44. In this state, the open/close mechanism describedabove is in the open state by the function of the guide block.

FIG. 30 shows a sample measurement state. The sample container 36 whichis set as a measurement target is placed in the sample measurementchamber 34 by the function of the lifting/lowering mechanism 40. Inother words, the sample container 36 is placed between the pair ofphotomultiplier tubes 174 and 176 in a non-contact state with thephotomultiplier tubes. In the sample measurement state, the shuttermechanism is operated across the lifting/lowering path 28. In FIG. 30,the lead block 148 is inserted across the lifting/lowering path 28.Along with the lead block 148, a light-shielding plate to be describedlater is inserted across the lifting/lowering path 28.

FIG. 31 shows a YZ cross section of the sample measurement device. FIG.31 shows a non-measurement state. In FIG. 31, the head 44 is at aposition of a lifted end. The lifting/lowering mechanism 40 has avertical plate 182, and a rail 184 is attached on the vertical plate182. A slide block 186 is provided to be movable in the up-and-downdirection with respect to the rail 184. A lower end of the shaft 43 isattached to the slide block 186. The head 44 is attached to an upper endof the shaft 43. A drive force of a motor 188 is transmitted to theslide block 186, which is then driven in the up-and-down direction. Withthis movement, the shaft 43 and the head 44 also move in the up-and-downdirection. The vertical plate 182 is connected to a base frame 181 and abase plate.

A case to be described later is fixed on the base frame 181. Theshielding structure 178 is provided on the base plate 180 in a manner towrap the sample measurement chamber 34 and the case. As described above,the shielding structure 178 is formed from lead or the like.

The shutter mechanism 42 includes the upper shutter mechanism 42A andthe lower shutter mechanism 42B. The upper shutter mechanism 42A has thelead block 148 that blocks extrinsic radiation, and the tube guide 146.The lower shutter mechanism 42B has the shielding plate to be describedlater in detail.

FIG. 32 shows the YZ cross section of the sample measurement device asan enlarged view. FIG. 32 shows the sample measurement state. The samplecontainer 36 is placed in the sample measurement chamber 34. Asdescribed above, the shutter mechanism 42 has the upper shuttermechanism 42A and the lower shutter mechanism 42B. The upper shuttermechanism 42A has the lead block 148 and the tube guide 146. In FIG. 32,the lead block 148 is placed across the lifting/lowering path. Inaddition, the light-shielding plate 150 is inserted across thelifting/lowering path. In this state, the extrinsic radiation from aboveis blocked, and, at the same time, the extrinsic light from above isblocked. With this configuration, a sample measurement of high precisioncan be realized.

FIG. 33 shows a lower part of the sample measurement chamber as anenlarged view. FIG. 33 shows the sample measurement state. The uppersurface of the base frame 181 forms a reference level 206. That is, inthe movement control of the sample container 36 in the up-and-downdirection, the reference level 206 forms an origin point in the Zdirection.

A case 190 having a shape to wrap the sample container 36 is provided onthe base frame 181. On the outer side of the case 190, the shieldingstructure 178 is provided. An opening is formed at the center of thebase frame 181, and the shaft 43 passes through the opening. The body ofthe head 44 is attached to the upper end of the shaft 43. Specifically,a well 192 is formed in the body of the head 44, and the upper end 43Aof the shaft 43 is inserted into the well 192. A ring-shaped stopper 193is provided on the upper end 43A, and a spring 196 is placed between thestopper 193 and a bottom surface 192A of the well 192.

A top plate 194 is provided in a manner to cover the well 192. The topplate 194 is formed as a layered structure in the present embodiment,and includes at least an elastic sheet at a lower side and a metalreflective layer at an upper side. Alternatively, optical reflection maybe produced by painting. The lower elastic member sheet functions as alight-shielding sheet. For example, as shown in FIG. 18 which hasalready been described, two screw members are used to attach the topplate 194 on the body of the head 44. With such a configuration, asuperior light-shielding state is formed.

Because the spring 196 is provided on the upper end 43A of the shaft 43,even if the shaft 43 is lowered slightly excessively, the excess isabsorbed by the spring 196. Therefore, the head 44 can be easily loweredto a point where the lower surface of the head 44 closely contacts theupper surface of the base frame 181; that is, the reference surface. Inaddition, in such a close contact state, as will be described below, asuperior light-shielding state can be formed. The stopper 206 is fixedlyplaced below the head 44 in the shaft 43, and even when the spring 196is changed from a compressed state to an elongated state, the amount ofchange is restricted by the stopper 206. In other words, the elongationof the spring 196 is allowed until the stopper 206 contacts the lowersurface of the head 44.

Next, the light-shielding structure (inner light-shielding structure)will be described. The light-shielding structure is a structureconstructed over the upper surface of the base frame 181 and the lowersurface of the head 44.

A first ring groove 198 is formed on the upper surface of the base frame181 in a manner surrounding the opening through which the shaft 43passes. In correspondence to this structure, a first ring protrusion 202is formed on the lower surface of the head 44. In a state where the head44 is positioned at the lowermost position; that is, the definedposition, the first ring protrusion 202 enters the first ring grove 198,and a state is formed in which the protrusion and the groove are fitted.In this case, the shaft 43 is slightly lowered exceeding the lowermostposition of the head by a controller (not shown). With this process, anelastic action by the spring 196 is realized. That is, a force pressingthe head 44 downward is produced by the spring 196. As a result, asuperior close contact state is formed between the first ring groove 198and the first ring protrusion 202. That is, a superior light-shieldingstate can be formed. Thus, it becomes possible to reliably blockextrinsic light entering the inside of the sample measurement chamberalong the outer surface of the shaft 43 and the upper surface of thebase frame 181. In addition, with the fitting between the first ringgroove 198 and the first ring protrusion 202, a positioning function inthe horizontal direction can be obtained for the head 44, with which thesample container 36 can be appropriately positioned in the samplemeasurement chamber.

In the present embodiment, an outer light-shielding structure isconstructed at an outer side of the inner-light shielding structuredescribed above. Specifically, a second ring groove 200 is formed on theupper surface of the base frame 181 in a manner to surround the firstring groove 198. On the other hand, a second ring protrusion 204 isformed on the lower surface of the leg of the case 190 in a manner tosurround the first ring protrusion 202. The second ring protrusion 204enters the inside of the second ring groove 200 in the assembly state,to form a fitted state between the protrusion and the groove. With thisconfiguration, it becomes possible to reliably block the extrinsic lightattempting to enter the inside of the sample measurement chamber fromthe periphery of the base frame 181 along the upper surface of the baseframe 181.

The extrinsic light entering the head 44 along the outer surface of theshaft 43 is blocked at the inside of the head 44. That is, the top plate194 has the light-shielding sheet, which is fixed in a closely contactedmanner with respect to the body of the head 44, and the extrinsic lightis confined in the head 44 by the light-shielding sheet. In other words,intrusion of the extrinsic light through a gap between the top plate 194and the body of the head 44 is prevented. In order to achieve sufficientlight shielding in the head 44, desirably, a sheet made of a blackelastic material is used as the light-shielding sheet. The body of thehead 44 is formed from, for example, a hard resin or the like. The baseframe 181 is formed from a metal or the like. The case 190 is formedfrom a metal.

(F) Light-Shielding Unit (FIGS. 34-36)

FIG. 34 shows a first perspective view of the shutter mechanism 42.Specifically, FIG. 34 shows the shutter mechanism 42 as viewed fromdiagonally above.

As already described, the shutter mechanism 42 has the upper shuttermechanism 42A and the lower shutter mechanism 42B. The upper and lowershutter mechanisms are attached to a fixed structure. Specifically,fixed blocks 208 and 210 are provided in parallel with each other, and ashaft 212 and a guide member 214 are placed between the fixed blocks. Ablock is attached in a slidable manner on the shaft 212, and forms apart of a movable member 220. The guide member 214 forms a guide rail,and a roller 224 of the movable member 220 rotationally moves on theguide member.

A block base 218 spreading in the horizontal direction is provided overthe fixed block 208 and the fixed block 210. The block base 218 is amember corresponding to the top frame 122 shown in FIG. 13. That is, theguide block 30 is fixed on the block base 218. A motor 226 forms asingle drive source in the slide mechanism 182, and a feed screw 216 isdriven by the motor 226. In the present embodiment, the feed screw 216is formed by a trapezoidal screw. A block (not shown) is connected tothe trapezoidal screw 216, and, with the rotation of the feed screw 216,the movable member 220 having the block moves in the horizontaldirection. The upper shutter mechanism 42A is attached to a movableframe of the movable member 220, and, similarly, the lower shuttermechanism 42B is also attached to a movable frame 222.

FIG. 35 shows a second perspective view of the shutter mechanism 42.Specifically, FIG. 35 shows the shutter mechanism 42 as viewed fromdiagonally below. The movable member 220 includes the upper shuttermechanism 42A and the lower shutter mechanism 42B. The lower shuttermechanism 42B has the light-shielding plate 150. The light-shieldingplate 150 is formed from, for example, a thin metal plate, and examplesof the materials forming such a metal plate include zinc, copper, andthe like. Preferably, the light-shielding plate 150 is formed from ametal having a light-shielding function and also a function to block abraking radiation. A braking radiation is a radiation secondarilyproduced when the extrinsic radiation is blocked by the lead block.

The light-shielding plate 150 has a body 150A forming a horizontalportion, and a bent portion 150B continuous from the body 150A, and thebent portion 150B forms a vertical portion. Further, the bent portion150B is connected to an attachment portion 150C, and the attachmentportion 150C is fixed on the movable frame described above. On a baseend side of the body 150A of the light-shielding plate 150, an elasticmember block 228 is provided. Specifically, the elastic member block 228has a slit 228A formed therethrough in the horizontal direction, and apart of the body 150A; in particular, a part of the base end, isinserted into the slit 228A. The slit 228A and the body 150A are notfixed with respect to each other, and a relative horizontal movement isallowed. The elastic member block 228 may be fixed on the movable frameor simply attached to the body 150A. The elastic member block 228 isformed from, for example, a rubber member or the like. In FIG. 35, aslit structure (fixed structure) which receives the body 150A in thelight-shielding plate 150 is omitted in the drawing.

FIG. 36 shows a cross sectional diagram of the shutter mechanism 42. Asdescribed above, the upper shutter mechanism 42A has the lead block andthe tube guide 146 arranged in the horizontal direction. When the leadblock is at the retracted position, the tube guide 146 is positioned onthe lifting/lowering path, and the centering function (alignmentfunction) with respect to the sample container or the like is realized.

Specifically, on the inner surface of the tube guide 146, a taperedsurface 146A is employed at the upper end portion, and a tapered surface146B is employed at the lower end portion. With these inclined surfaces,when the sample container moves from the upper part toward the lowerpart or when the sample container moves from the lower part toward theupper part, even if there is a position deviation in the horizontaldirection, the sample container can be positioned at an appropriateposition in the horizontal direction by the function of the inclinedsurfaces. Alternatively, the alignment function with respect to the headmay be realized.

Next, the lower shutter mechanism 42B will be described. FIG. 36 shows aslit structure 230. The slit structure 230 forms a part of the lowershutter mechanism 42B, and is a fixed structure. The slit structure 230can be roughly divided into an upper plate 232 and a lower plate 234,and a slit is formed between the plates. The periphery of the slit issealed except for the entrance which accepts the light-shielding plate150. That is, entrance of light into the slit from the outside isblocked.

The light-shielding plate 150 is in the retracted position in FIG. 36,and, in this case, only the tip of the light-shielding plate 150 entersthe slit structure 230. The light-shielding plate 150 is at a positioncompletely deviated from the lifting/lowering path.

The elastic member block 228 is attached to the base end side of thelight-shielding plate 150. The elastic member block 228 has thehorizontal slit 228 a, and the light-shielding plate 150 penetratestherethrough. When the shutter mechanism 42 executes the shutteroperation, the movable portion in the upper shutter mechanism 42A andthe movable portion in the lower shutter mechanism 42B move from theretracted position toward a front position. With this configuration, thelead block is inserted at the upper side on the lifting/lowering path,and the light-shielding plate 150 is inserted to the lower side. Withsuch a double shutter state, the extrinsic radiation is blocked, and, atthe same time, the extrinsic light is blocked. The slit structure 230 isfixed at the upper end of the case 190 described above.

When the movable portion in the lower shutter mechanism 42B reaches theforward position, the end of the slit structure 230 is inserted in arecess 228B serving as a depression formed in the elastic member block228, and an end surface of the end strongly contacts a back surface ofthe recess 228B. In other words, the slit structure and the recess arestrongly and closely contacted with each other. With this process, theintrusion of the extrinsic light into the inside of the slit through theslit entrance of the slit structure 230 can be reliably blocked. On theattachment end side of the light-shielding plate 150, a certaindeflection portion such as the vertical portion is present, and, whenthe light-shielding plate 150 is pressed to the front end, the reactionthereof can be absorbed by the base end side of the light-shieldingplate 150.

According to the shutter mechanism of the present embodiment, shieldingof the radiation and shielding of the light can be simultaneouslyexecuted with a single drive source and a single slide mechanism, and,thus, it is possible to simplify the mechanism, and at the same time,the control. In addition, because the light-shielding plate is formedfrom a member having a function to block or attenuate the brakingradiation, an advantage can be obtained in that, even if the brakingradiation is produced at the lead block, reaching of the radiation tothe sample measurement chamber can be effectively reduced.

Further, because the elastic block is provided at a root side of thelight-shielding plate and the intrusion of the extrinsic light into theinside of the slit structure is blocked by close contact of the slitstructure to which the light-shielding plate is inserted and the elasticmember block, an advantage can be obtained in that the extrinsic lightentering from the periphery can be effectively blocked in addition tothe extrinsic light coming in from above and through thelifting/lowering path. In the present embodiment, because the samplemeasurement chamber is provided on a lower side of the transport table;that is, because there is no shaft in the lifting/lowering path when theshutter mechanism is operated, an advantage can also be obtained in thatthe structure of the shutter mechanism can be simplified.

(G) Alternative Configuration of Adapter (FIGS. 37-40)

Next, an alternative configuration of the adapter will be described withreference to FIGS. 37-40.

FIG. 37 shows a first perspective view of an adapter 236 according to asecond preferred embodiment of the present invention. The adapter 236has an annular frame 238 and a pair of arms 240 and 242 connectedthereto. The arm 240 and the arm 242 have shapes symmetric from eachother. The arm 242 will be described as a representative of the twoarms. The arm 242 has an upper portion 242A, a wave-shaped portion 242B,and a lower portion 242C. A lower end structure 246 is formed in thelower portion 242C. Similarly, the arm 240 has a lower end structure244.

The lower end structure 244 and the lower end structure 246 has astructure symmetric from each other. The lower end structure 244 has arib 248 protruding in the horizontal direction and a support plate 250fixed thereto. An upper end 250 a of the support plate 250 has aninclined portion inclined in the inner side. A reinforcement plate 252extending from the arm body is connected to an intermediate position ofthe support plate 250.

FIG. 38 shows a second perspective view of the adapter 236. As describedabove, in the arms, the lower end structures 244 and 246 are formed.

Functions of the lower end structures 244 and 246 will now be describedwith reference to FIG. 39. When an opening force 258 is applied to theouter side in the horizontal direction by the contact with the guideblock, the lower end structures 244 and 246 move toward the outer sidein the horizontal direction. This movement is shown by a referencenumeral 260. On the other hand, when an excessive pressing force 254 isapplied from above and through the sample container in a state where thetwo arms 240 and 242 are in the closed state, the upper end portion ofthe support plate is deformed in a manner to fall toward the inside asshown by a reference numeral 256. With such a deformation, all or aprimary portion of the pressing force 254 from above is absorbed. Inother words, because the pressing force is concentrated in thedeformation portions of the lower end structures 244 and 246, no openingmovement of the two arms 240 and 242 as described above is caused.

In the first preferred embodiment of the present invention describedabove with reference to FIG. 12 or the like, the stopper connected tothe deformation portion is used. In contrast, in the present embodiment,erroneous operation by the pressing force from above is prevented usingthe deformation portion which moves to fall toward the inside. In bothpreferred embodiments, deformation is effectively used.

FIG. 40 shows a cross sectional diagram of the rack. The adapter 236described above is attached on the rack body 262. Reference numerals240A and 242A show a state where the arms are opened, and referencenumerals 240B and 242B show a state where the arms are closed. Asdescribed above, even when the pressing force is applied from above inthe closed state, the pressing force is absorbed by the elasticdeformation of a part of the structure, and the opening movement of thepair of arms is effectively prevented. In the case where the adapteraccording to the second preferred embodiment of the present invention isused also, the guide block shown in FIG. 18 or the like is used.

1. A sample measurement device, comprising: a rack having a samplestorage unit; a transporting mechanism that transports the rack; and anopen/close mechanism provided in the sample storage unit, that holds asample container in a closed state, and that releases the samplecontainer in an open state, wherein the open/close mechanism changesfrom the closed state to the open state when an opening force in ahorizontal direction is received, and maintains the closed state when apressing force in a vertical direction is received through the samplecontainer.
 2. The sample measurement device according to claim 1,wherein the open/close mechanism has: a movable member that supports alower surface of the sample container at an immediately-below positionof the sample container in the closed state, and that moves from theimmediately-below position to a retracted position deviated to an outerside in the horizontal direction during a state change from the closedstate to the open state, and a deformation member that deforms by apressing force when the pressing force is applied, so as to restrictmovement of the movable member to the retracted position.
 3. The samplemeasurement device according to claim 2, wherein the open/closemechanism has a pair of arms, the movable member is formed by a pair oflower ends of the pair of the arms, and the deformation member is formedby a pair of deformation portions of the pair of the lower ends.
 4. Thesample measurement device according to claim 3, wherein each of the armshas: an upper end connected to a body of the rack; a bending portionthat is a portion continuous from a lower side of the upper end and thatelastically bends toward an outer side in the horizontal direction inthe open state; and a lower end that is continuous from a lower side ofthe bending portion and that is one of the pair of the lower ends, andthe bending portion produces an elastic recovery force in the openstate.
 5. The sample measurement device according to claim 4, whereineach of the lower ends has: a base end connected to the lower side ofthe bending portion; a contact end that contacts the lower surface ofthe sample container in the closed state; a curved portion providedbetween the base end and the contact end and that is one of the pair ofthe deformation portions; and a stopper piece connected to the contactend that moves in an up-and-down direction along with the contact end,the curved portion elastically deforms when the pressing force isapplied, to lower the contact end and the stopper piece downward, andthe rack has an opening structure that allows an opening movement of thelower end when the stopper piece is at a normal level and that collideswith the stopper piece to restrict the opening movement of the lower endwhen the stopper piece is at a lowered level.
 6. The sample measurementdevice according to claim 5, wherein each of the lower ends has anattachment detachably attached to the lower side of the bending portion,and the attachment has the base end, the contact end, the curvedportion, and the stopper piece.
 7. The sample measurement deviceaccording to claim 5, wherein a guide block is provided on a transportsurface on which the rack is placed, and each of the lower ends has acontact member that contacts the guide block and receives an openingforce in the horizontal direction.
 8. The sample measurement deviceaccording to claim 5, wherein the body of the rack has: a pair of upperopenings that store the pair of the bending portions of the pair of thearms; and a pair of lower openings that form the opening structure, thatallow passing of the pair of the lower ends when no pressing force isapplied, and that collide with the pair of the stopper pieces torestrict the passing of the pair of the lower ends when the pressingforce is applied.
 9. The sample measurement device according to claim 4,wherein each of the arms has an arm body having the upper end and thebending portion, and each of the lower ends has a support plate that isa member that extends from a lower end of the arm body in an upwarddirection, that contacts the lower surface of the sample container, andthat deforms in a manner to fall toward an inner side in the horizontaldirection by the pressing force.